Hydraulic drive mechanism



4May 14, 1940. H. N. Buss Em. 2,200,832

HYDRAULIC DRIVE yMECHANISM Filed June 9, 1939 Patented May 14, 1940 PATENT OFFICE HYDRAULIC 'DRIVE 'MEGHANISM opmaat-ion June 9, 193.9., semi Nc. .zussie 9 Claims.

l Iliirs invention relates to hydraulicdrive mech anism of a `typewhich is Aadapted for use, for en ample, in driving the feed screw cfa stoker. 'In a transmission vof this type, provision is made for adjusting the 'length of stroke of the reciprocating drive member, by adjusting a valve which controls the escape of the pressure fluid at the .end of the Apiston stroke. The invention deals particularly with this valve mechanism, and has `as -its sobfject `Vto provide an improved .hydraulic transmission of the type indicated, `wherein the valve is of relatively simple and inexpensive, ,yet exceeding-ly durable construction, involving no moving parts, and yet providing iorvery fine adjustments ofthe piston stroke.

Specifically, the invention contemplates an arrangement wherein the stroke of the piston isdetermined by the escape oiuid-througha .port in a lateral wall -of the cylinder in which the piston operates, which port is adjustable lin vextent by means of 'avalve .elementhaving a portion exF tending into the port and defining `one extremity thereof.'

An embodiment of the invention is illustrated in the accompanying drawing, in which:

Fig. '1 isan axiallyy sectional `viewoi a hydraulic drive mechanism incorporating the invention, the piston being illustrated at the end oiits return stroke;

Fig. 2 isa detailed transverse sectional view ofthe vaive, and adjacent portions of the transmission, the piston Abeing lshown rat the' forward limit yo'f its advancing stroke; Y

Fig. 3 is a detailed transverse sectional rView taken on the line of of Fig. 2; and

Fig. 4 is a detailed sectional View taken 0n the line -A of Fig. 2.

.Asanillustration of one formin whicl'i the invention. may be embodied, we have shown in Fig. 1.a portionoi astoler drive of the general 'type illustrated in the pending application, Serial No. 219,7.14of .I-I. yN. Bliss.andG-..E...E'enton, filed July 18, 1193.8, for Feeding apparatus. 'Reference is made to thatapplication forfdetailsof construcr non 'of the ,feedingapperates in .which the invention is embodied..

A hydraulic drive mechanismof this type may embody a transmissionfcase il! having studs Alrl by'which it may be securedfto one'end-oi a conveyor screw conduit, and having in its central region a bearing l2 in which may be mounted, for combined reciprocating andoscillating movements, a piston rod i3 having at one end a squared or splined shank I4 adapted ,to form a (Cl. 12in-'135) l driving Vengageonsnt with rthe socket endoi -a conveyor screw.

To one end of the transmission case l is secured a .cylinder 15 having a head it. lMounted upon the rear end oi. the piston rod i3, 'as by means of a nut il, and snugly fitted within the bore of the rcylinder l5, is a piston i8 which forms, between itself yand the end wall I6, a

Ichamber i8, and between itself and the rear wall 29 of the transmission case til, a chamber 2l.`

.he piston i8 is adapted to vbe driven back' and `iertl'l by fluid underl pressure introduced alternately into the chambers l-S Vand 2l.

Fluid under pressurev isv supplied to the piston chambers by means of a pump, indicated in dotted lines at 22, and is directed alternately to the chambers i9 and 2.! by means of a directing valve 2-3, rotatable in a valve cylinder M Aand adapted to directfluid vfrom the pump alternateltr through a duct Bleading tothe piston chamber i9, and a duct 26 :leading to the piston chamber 2l.

In lthe lateral wall of vthezcylinder l is a fluid escape port 2'! one laxial .extremity of which is dened 4by the wall of the cylinder 'l5 and the other .axial extremity of which is dened by an axially adjustable key 28 forming part'of anaxiallyladjustable valve 23. The `valve 29 includes the -key `portieri 28 and a cylindrical ksleeve portion 3l! which is axially7 slidable .in a cylindrical valve chamber 3l formed integrally with the piston. cylinder i5. The hollow interior oi' the sleeve 3.53 forms a duct 32 which communicates at the forward end of the valve, with the interior of the transmission case lll through an opening:33 in the rear wall -Zther-eof. A slot 313 inthe sleeve portion of lthe fvalve, just rearwardly of the key i8, vestablishes communication between the port 251 and the duct 32, `so that-when the piston i8 is at either end of its stroke, pressure `fluid mayescape past the piston through the port 21, the 'slot 34 andthe duct 32, into the sump 35 formed in the bottom of the `transmission lcase lil, from which it may be drawn through an yirl-- let ftube 3S and filter 3l into the pump y2?! yfor redistribution back to the chambers t9 and 2l.

The limit of forward movement of the piston is rixedly determined by uncovering the port v2l' by the rear side of the 'piston i8 so as toprovide a passageway between the rear side -of the pistonand the fixed rear extremity of the port 2l as shown in Fig. 2. The limit of return stroke of the piston is adjustably determined by uncovering theport 21 by the forward side of the pistonyso as to provide a passageway 31 between 32, to the sump 35. The valve 23, which is rotated b-y worm-gearing indicated generally at 38 in dotted lines, will, shortly after the piston has vreached its forward limit of travel, cut 01T the..

flow of pressure iiuid through the duct and divert the flow through the duct 26 into the chamber 2|. The piston will then commence to move rearwardly until the port 21 is uncovered to establish the passage 31. The pressure uid in the chamber will then be vented through the pas sage 31 back to the `sump 35 until the valve 23 has again reversed the flow.

In the position of valve adjustment shown in Fig. l, the piston has a maximum length of stroke, being substantially in contact with the cylinder head I6 at the rear end of its stroke. As the valve 29 is adjusted to the right as viewed in Fig. 1, the port 21 will be uncovered, i. e., the passage 31 will be established at an earlier point in the return stroke of the piston. rAs a result, the stroke of the piston will be 'shortened, and the period of venting through the passage 31 will be lengthened.

The opening 33 in the wall 20 of the transmission case is of sucient diameter to receive the valve Z9 as the latter is shifted axially.

Axial shifting of the valve is accomplished by an adjusting screw 40 having a helical groove 4i into which is extended a pin 42 mounted in the sleeve portion of the valve 29 as shown in Figure 3. The screw has an enlarged shaft portion 44 which extends through a packing gland 45 and carries at its outer end a dial knob 46. The screw 40 is formed with an annular groove 41 into which projects the two separated halves of a two-piece washer 48 secured between the packing ring 49 of the packing gland 45 and a shoulder 5I) forming the forward extremity of the packing gland chamber. The washer 48 forms an end thrust bearing for the adjusting screw.

The dial knob 45 may be provided with a dial scale 5I adapted to cooperate with an indicator mark 52 embossed on the rear wall I5 of the cylinder I5.

As the dial knob 46 is rotated, the screw 40 will coact with the pin 42 to move the valve 29 axially, thereby adjusting the length of the port 21. The exact length of piston stroke may be read directly upon the dial scale. i

The inner extremity of the valve key 28 vis shaped to form a continuation of the bore of the cylinder I5, as shown in Figure 4. Thus the key in effect forms a part of the wall of the cylinder against which the piston I8 will seal as soon as it has closed the port 26.

The control knob 46 is provided on the forward side of its rim, with a lug 55 adapted to engage a projection 56 on the cylinder head lli at the extremities of valve adjustment. Thus the full range f valve adjustment is determined by slightly less than one complete rotation of the knob 46.

'I'he present invention has the advantage that the valve possesses no moving parts to produce Wear. The valve may be adjusted more rapidly and with greater facilityth'an prior valves, and has a better visibility for adjustment. It is less expensive than prior valves because it permits the use of a die casting for the control knob as well as for the valve. It permits the extension of the piston rod I3 through the cylinder head I6 if this should be desired, as for instance in order to permit the use of the piston rod extension for driving other mechanism. The invention also has the advantage that the cylinder head I6 may be cast in a single unit and simply bolted onto the transmission'case I0 as at 51.

The reciprocating movement of the piston rod.

I3 is transformed into a combined reciprocating and oscillating movement, by means'of a clutch ring 60, threaded upon a screw threaded portion SI of the piston rod I3, adapted when the piston rod I3 moves rearwardly to engage a coacting clutch element 62 secured to the rear wall 20 of the transmission case and thereby to force the rod to rotate and, upon forward movement, to disengage from the clutch element 62 and engage a thrust bearing 63 so as to allow the clutch element 62 to freely rotate and the piston rod I 3 to advance without rotation.

We claim: f

1. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering Huid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, a port in the side wall of said cylinder, adapted to be uncovered by said piston at the end of its stroke, and means for varying the eiective dimension of said port in an axial direction so as to vary the point of piston stroke at which the port is uncovered.

2. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, and means for vary-V ing the stroke of said piston, comprising anescape port in a' side wall of said cylinder, and a valve element partially iilling said port and adjustable f axially therein so as to variably restrict the axial dimension thereof for Varying the point of uncovering of said port by the piston.

3. In a hydraulic drive mechanism, a cylinder,

a reciprocable piston therein, means for alter-..

nately delivering uid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, and means for varying the stroke of said piston, comprising a valve chamber formed in a side wall or said cylinder,

said wall having a uid escape port communicating with said valve chamber, and an axially adjustable Valve in said chamber including a key portion extending into said port, partially filling the same and variably restricting the axial dimension thereof for varying the point of uncovering of said port by the piston.

4. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, and means for varying the stroke of said piston, comprising a valve chamber formed in a side wall of said cylinder, said wall having a fluid escape port communicating with said valve chamber, a key-shaped valve axially movable in said'chamber, adjusting means y including a screw extending through an external Wall of said valve chamber and into the valve element and cooperating ytherewith for movingl u the same axially in the chamber, said valve element having a key portion projecting into said port, partially lling the same, and variably restricting the axial dimension thereof for varying the point of uncovering of said point by the piston. r

5. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, and means for varying the stroke of said piston, comprising a valve chamber formed in a side Wall of said cylinder, said Wall having a fluid escape port communieating with said valve chamber, and an axially adjustable valve in said chamber having a key portion projecting into said port, variably restricting the axial dimension thereof for varying the point of uncovering of said port by the piston, and having an axial duct through which the fluid coming from said port may escape through the valve.

6. In a hydraulic drive mechanism, a cylinder` a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, and means for varying the stroke of said piston, comprising a cylindrical valve chamberv formed in a side Wall of said cylinder, said wall having a uid escape port communicating with said valve chamber and an adjusting element extending through an exterior wall of said valve chamber and cooperating with one end of said sleeve portion for adjusting the valve axially, the other end of said sleeve portion providing a duct for escape of the iiuid through said valve.

7. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sidesof said piston for driving the same back and forth, and means for varying the stroke of said piston, comprising a cylindrical valve chamber formed in a side wall of said cylinder, said Wall having a fluid escape port communicating with said valve chamber, a valve including a cylindrical sleeve portion axially slidable in said chamber and a key portion projecting into said port, partially filling the same, and variably restricting the axial dimension thereof for varying the point of uncovering of said port by the piston, an adjusting screw extended through an exterior Wall of said valve chamber along the axis of said chamber, and into said sleeve portion, a pin mounted in said sleeve portion and coacting with a helical groove of said adjusting screw whereby rotation of the adjusting screw vvill move the valve axially, a hand wheel on the outer end of said adjusting screw,

and meanscooperating with said hand wheel for indicating the position of adjustment of said adjusting element.

8. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, and means for varying the stroke of said piston, comprising a Valve chamber formed in a side Wall of said cylinder, said wall having a fluid escape port communicating'with said valve chamber, and an axially adjustable valve in said chamber having a key portion extending into said port and variably restricting the axial dimension thereof for varying the point of uncovering of said port by the piston, the inner end of said key portion being shaped to form a continuation of the cylindrical inner surfaces of the cylinder.

9. In a hydraulic drive mechanism, a cylinder, a reciprocable piston therein, means for alternately delivering fluid under pressure to said cylinder on opposite sides of said piston for driving the same back and forth, a port in the side Wall of the cylinder, a fixed extremity of which is adapted to be uncovered by one side of said piston at one end of the piston stroke, and the opposite extremity of which is adapted to be uncovered by the other side of the piston at the other end of the piston stroke, and means for axially adjusting said last mentioned extremity of the port so as to vary the point of piston travel at which the.

port is uncovered and thereby vary the length of the piston stroke.

. HAROLD N. BLISS.

GEORGE E. FENTON. 

